NMR Rate Measurements of Glyoxal and Methylglyoxal Reacting with Amine and Ammonium Sulfate

NAZIN SEDEHI, Lelia Hawkins, David De Haan

University of San Diego

     Abstract Number: 820
     Last modified: July 22, 2011

Abstract
The reactions of glyoxal and methylglyoxal with ammonium salts and amines have been proposed as significant sources of atmospheric organic aerosol. Using these chemicals involved with aerosol production and sequential 1H-NMR scans, reaction rates were analyzed as a function of pH and temperature. Glyoxal and methylglyoxal were combined with methylamine, glycine, arginine, or ammonium sulfate and an internal standard, acetonitrile, along with deuterated acetic acid for pH control. Initial reaction rates were extracted from the data and used to calculate rate constants and activation energies. All reactions increased in rate as temperature and pH increased, and methylglyoxal reactions were observed to be significantly faster than corresponding glyoxal reactions.